LITTLE ROCK (AP) — Two opponents in the hotly-contested Arkansas U.S. Senate race joined with officials from a pipe manufacturer Monday to press for approval of the Keystone XL Pipeline, which would move crude oil from Canada to U.S. refineries.

Democratic U.S. Sen. Mark Pryor and Republican U.S. Rep. Tom Cotton, who is challenging Pryor, appeared together at Welspun Corp.'s 800-acre campus at the Port of Little Rock, where they called on President Barack Obama to approve the pipeline project.

Welspun Tubular LLC President and CEO David Delie showed reporters 358 miles of pipe made for TransCanada, the company building the pipeline, that's stacked up on 80 acres adjacent to an idle factory.

"If that pipeline was approved, we'd be running the mill right now," Delie said. "This is costing jobs here and changing the business model for everybody."

Critics of the pipeline want the project called off out of concern that it will put groundwater at risk and add to pollution.

The pipeline, 36 inches in diameter and 1,179 miles long, would run from Hardisty, Alberta, to Steele City, Nebraska. Trans Canada says the line will send Canadian crude oil to refineries in the United States and provide opportunities for growth in crude production in Montana, North Dakota, Oklahoma and Texas.

A segment from Steele City to storage facilities in Cushing, Oklahoma, is already complete. The line would connect to Texas refineries along the Gulf Coast.

Pryor and Cotton, who are running expensive and bitter campaigns, each said the Keystone XL would provide jobs and a safer way than railcars or older pipelines to transport Canadian oil to refineries.

Cotton accused Obama of "ideological foot-dragging," saying the president is following the wishes of the left in the Democratic Party.

Pryor said giving the pipeline the green light makes sense on a number of levels, adding that he's been "in a different place" than the president on the issue.

"It's by far the safest and most economical thing to do," Pryor said.

An energy efficiency bill was expected to come to a vote Monday in the U.S. Senate, and Pryor boarded a plane headed back to Washington, D.C., after the event at Welspun.

The bi-partisan bill appeared headed for failure after Senate Majority Leader Harry Reid, D-Nev., blocked amendments on the bill, including a measure that would approve construction of the proposed Keystone XL pipeline from Canada to the United States.

Backers of the project say they need the bill to end delays by the Obama administration in deciding whether to approve it.

Phillip Wallace of Bald Knob, the business representative for the Pipeliners Union, Local 798, in Tulsa, Oklahoma, said the Keystone XL would be state-of-the-art and safer than lines now in operation. He pointed to the Exxon-Mobile pipeline rupture in central Arkansas that forced 20 families in Mayflower from their homes and noted that line was built in the 1940s.

Wallace also said that Canadian oil will find its way to market via rail, which he said is dangerous, or by being sold to other countries. Wallace noted the eight significant accidents involving railcars hauling crude oil from Canada or North Dakota, the most recent in Lynchburg, Virginia. In Lac-Megantic, Quebec, Canada, 47 people were killed last year when an oil train exploded at night in the middle of town.

Delie said Trans Canada has paid for the pipe stacked up at the factory but is using other inventory for current construction. Approval of the pipeline would return to their jobs 220 workers, who are now laid off. He said the company's Little Rock has about 500 people working now, down from 800.

About 50 people will be needed when it's finally time to ship the stored pipe, a job that Delie said would take six to nine months. If Keystone XL is approved, there will be more jobs created to fill needs from janitorial service to equipment maintenance and repair, he said.

Welspun has hundreds of unused acres, which Delie said are available for expansion.

"We're hoping the efforts in the Senate this week will pay some dividends," Delie said.